Handle spaces in paths when generating caches

Fixes zsh-users#582

Current antigen branch doesn't properly handle spaces in paths when
generating caches, so if your antigen plugins live in a path with
spaces, the resulting $ADOTDIR/init.zsh will have improper paths for
fpath and path.

We'll address this by moving away from arrays when generating the _PATH
and _fpath variables for cached output, and will instead append strings
wrapped in double quotes. Then, when actually creating the caches, we'll
again avoid zsh array parameter expansion and instead just insert the
string list. This approach sidesteps a number of subtle issues that
arise when relying on arrays, and results is a very straightforward
cache file.

Author: Ryan Nielsen

bin/antigen.zsh

@@ -1818,8 +1818,8 @@ typeset -g _ZCACHE_CAPTURE_PREFIX
       fi
       _sources+=("source '${record}';"$'\n')
     elif [[ -d $record ]]; then
-      _PATH+=("${record}")
-      _fpath+=("${record}")
+      _PATH+="\"${record}\""
+      _fpath+="\"${record}\""
     fi
   done
 
@@ -1834,7 +1834,7 @@ antigen () {
   return 0;
 }
 typeset -gaU fpath path
-fpath+=(${_fpath[@]}) path+=(${_PATH[@]})
+fpath+=(${_fpath}) path+=(${_PATH})
 _antigen_compinit () {
   autoload -Uz compinit; compinit $ANTIGEN_COMPINIT_OPTS -d "$ANTIGEN_COMPDUMP"; compdef _antigen antigen
   add-zsh-hook -D precmd _antigen_compinit

src/ext/cache.zsh

@@ -34,8 +34,8 @@ typeset -g _ZCACHE_CAPTURE_PREFIX
       fi
       _sources+=("source '${record}';"$'\n')
     elif [[ -d $record ]]; then
-      _PATH+=("${record}")
-      _fpath+=("${record}")
+      _PATH+="\"${record}\""
+      _fpath+="\"${record}\""
     fi
   done
 
@@ -50,7 +50,7 @@ antigen () {
   return 0;
 }
 typeset -gaU fpath path
-fpath+=(${_fpath[@]}) path+=(${_PATH[@]})
+fpath+=(${_fpath}) path+=(${_PATH})
 _antigen_compinit () {
   autoload -Uz compinit; compinit $ANTIGEN_COMPINIT_OPTS -d "$ANTIGEN_COMPDUMP"; compdef _antigen antigen
   add-zsh-hook -D precmd _antigen_compinit